From its northern frontier with Macedonia to its port of Piraeus in the south, Greece was inundated with refugees and migrants after border shutdowns cascaded through the Balkans, stranding at least 20,000 in the country.

At Idomeni, a small community on the border with Macedonia, Reuters witnesses saw hundreds of families walking towards the frontier to join an estimated 3,000 more at a makeshift camp where many pitched tents in a field close to razor wire fence.

More than 500 km further south, hundreds of people were temporarily accommodated at a disused airport west of Athens. Sleeping mats were strewn across the terminal among biscuit wrappers as many women sat on the floor, some weeping.

"Planes bombed our homes, it was dangerous to stay there," said mother of three Rajiya Zara, 38, nine months pregnant. "I'm afraid for my children."

Between 300 and 400 people refused to stay at the airport, and took off on their own. "Help Us," a large piece of paper held by one said. "We are human, open the borders", read another, scrawled on a sleeping mat.